Design of Frustrated Lewis Pair in Defective TiO2 for Photocatalytic Non-Oxidative Methane Coupling

The efficient C-H polarization is the prerequisite for the low-temperature photocatalytic CH4 conversion, which however is restricted by the poor stretching ability of short-distanced lattice atoms. Herein, frustrated Lewis pair (FLP) composed of doped ion in TiO2 as Lewis acid (LA) and neighboring Ti-OH as Lewis base (LB) with a long distance (0.31-0.37 nm) were designed through DFT calculation and fabricated by hydrogenation treatment of metal-doped TiO2-SiO2 with macroporous-mesoporous structure. Benefitting from the long LA-LB distance and matched acid-base intensity, hydrogenated Ga-doped composite achieves superior C-H stretching with a high CH4 conversion rate (139 µmol g−1 h−1) to ethane. The photo-irradiation causes the electron excitation from Ga to Ti-OH according to the time-dependent DFT calculation and in situ EPR analysis, which promotes the formation and coupling of ·CH3. This work provides a key underpinning for regulating the characteristics of FLP for C-H activation and C-C coupling via light irradiation.

Indirect cytotoxicity evaluations of antibacterial raw silk fabric doped with calcium, copper and zinc on fibroblasts and osteoblasts

Antibacterial materials are widely used to prevent hospital-acquired infections. In our previous report, metal (calcium, copper or zinc)-doped raw silk fabrics were shown to possess strong antibacterial activities against Escherichia coli. However, antibacterial materials may occasionally be harmful to the human body; thus, in this study, we investigated the cytotoxicities of extracts from metal-doped raw silk fabrics with respect to fibroblasts and osteoblasts indirectly. Calcium-doped raw silk fabric demonstrated cytocompatibility with fibroblasts. Contrarily, copper- and zinc-doped raw silk fabrics remarkably decreased the cell densities of fibroblasts, indicating their cytotoxic effects. This observation could be attributed to the high concentrations of the released copper or zinc ions. However, calcium-, copper- and zinc-doped raw silk fabrics did not demonstrate any cytotoxic effects on osteoblasts because a high concentration of the serum alleviated the effects of these metal ions released from the fabrics. Thus, calcium-doped raw silk fabric is a promising antibacterial material that does not induce strong cytotoxicity. This study will facilitate the design of materials that are both antibacterial and safe.

Theoretical Design of Transition Metal-Doped TiO2 for the Selective Catalytic Reduction of NO with NH3 by DFT Calculations

Many transition metal oxides supported on TiO2 have been studied for selective catalytic reduction (SCR) of NO with NH3. However, the trade-off exists between the low-temperature activity and N2 selectivity....